[NSString # integerValue] is suck

IntegerValueSample.m

#import <Foundation/Foundation.h>

int main(int argc, char *argv[]) {
    @autoreleasepool {
        NSArray *befores = @[
          @"100", // => 100, a number
          @"10 0",  // => 10, a number
          @"00100",  // => 100, a number
          @"10blank", // => 10, not a number
          @"blank10",  // => 0, not a number
          @"blank200", // => 0, not a number
          @"" // => 0, not a number
        ];
        for (NSString *before in befores) {
            // http://stackoverflow.com/a/3474311
            {
                NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
                     NSNumber *number = [formatter numberFromString:before];
                     [formatter release];
                      NSLog(@"%@ is %@", before, (!!number ? @"a number" : @"not a number"));
            }
            int after0 = [before intValue]; // 最後にintに入れる場合、#integerValueとおなじ
            NSLog(@"result: %d", after0 - 1);
            int after = [before integerValue]; 
            NSLog(@"result: %d", after - 1);
            NSInteger after2 = [before integerValue];
            NSLog(@"result: %ld", after2 - 1);
            NSInteger *after3 = [before integerValue]; // たいへんなことになるよ
            NSLog(@"result: %ld", after3 - 1); 
        } 
    }
}